Barebone and budget minded DIY Headtracing (EDTracker approach)

[Kwings714]

Important
See download section for Joystick sketch/software (Oct 2018)

Sit still for like 5 to 8 seconds when plugin the USB. The IMU need to take sampling values for the Magnetometer and calculate for the Tilt Compensation.
Ideally, with the headphone/tracker at the intended operating position (on your head and adjusted)
The little octopus will be very jumping. That is drifting and the Tilt Compensation values was not obtained probably.

Hi All,
Here is my budget DIY HeadTracker ($30 or less, supposedly) I've been using/testing flight for about two months now.
Required only eight solder joins.

Required components;
$2.75 Micro USB cable (small and very flexible)
$15.95 MinIMU-9 v5 Gyro, Accelerometer, and Compass (3 DOF)
$8-19 Leonardo Pro Micro ATmega32U4 5V/16MHz (Cloned US shore)


1. Soldering iron and the Will to learn
2. DIY Obsession
3. If you can installed CLOD and conf files manipulation you shouldn't have any difficulty installing
Arduino open source and the required libraries
3a. Library installation tutorial (https://www.arduino.cc/en/Guide/Libraries)
4. The Sparkfun blinkies tutorial is a good example to get familiar with the Arduino Pro Micro and Arduino environment. (Load, Compile, Upload sketch, and Serial Monitor)
https://learn.sparkfun.com/tutorials...ple-1-blinkies


Software link;
1. https://www.arduino.cc/
1a. To view the IMU data, With the Arduino Application running, under Tools, Serial Monitor. Make sure the correct Board and the COM-PORT are set/and or selected if needed.

1b. To quickly visualize the output of the AHRS, you can run the Python test program (MinIMU-9-test.py). Also be sure to change to the correct com-port if you get an error message when try to run the Python program.

Python AHRS.jpg


2. https://github.com/pololu/minimu-9-ahrs-arduino
(A slight modification to the original AHRS code in order to work with OpenTrack or FaceTrackwithnoIR.
I wlll upload the modified code later and will link it here)

https://sourceforge.net/p/facetrackn...25&page=2#2368
https://sourceforge.net/p/facetrackn...read/9cbb2f4c/

3. https://github.com/pololu/lsm6-arduino
4. https://github.com/pololu/lis3mdl-arduino
4a. Use the Calibration to obtain the calibrated values.
(be patience when calibrating, repeat if drift is still exhibiting)
4b. The little Octopus will be very jumpy (OpenTrack started)

Hardware sample link;
1. https://www.pololu.com/product/2072
2. https://www.pololu.com/product/2738
2a, The advantage of using the Pololu minIMU-9 over other IMU is that the SCL(Clock) , SDA(Data) and GND (Ground) pins coincide with the Arduino Micro Pro Pinout
(https://learn.sparkfun.com/tutorials...view-pro-micro)
and you only need one wire to connect the VIN (2.5V-5V) to the VCC on the Arduino Micro Pro. When the components side facing down.
2b, The Y Axis has to be facing either forward or backward (not left/right) when mounted on your headset. This is due to the Gimbal Lock (±90° Y axis rotation not 180° like X and Z axis)
2c, IMPORTANT, avoid mounting the IMU directly on the exposed metallic headband of your headset. Its may cause magnetic interference with the IMU and MAY be contributing to the drifting issue. Hot Glue at the .99C store seem to do the trick for me.

3. https://www.sparkfun.com/products/12640
3a) There are 3.3V and 5 volt version
3b) Order the 3.3v version if you are planning to incorporate HC-05 BlueTooth later on (I am still working on this version)
3c) You can find many other clone of "Pro Micro ATmega32U4 5V 16MHz/3V 8MHz on Amazon, Ebay or Aliexpress "

4. Here is the software required link (https://theairtacticalassaultgroup.c...earchid=859201)

5. The IMU hardware/Software will self center if one of the three axis exceeded its range of rotation, 180° (X and Z) or (±90° for Y), so try to refrain from hitting the center button on OpenTrack shortcut. (Yes, even folks that have used other tracking device)

6. Let me know if you have/or find any issue(s), concern, comment or question? link to trouble shooting Pololu IMU.
https://forum.pololu.com/t/minimu-9-ahrs-code/4010 (Look for Z Gain values)

Capture1.jpgCapture2.PNGCapture3.PNGCapture4.PNG


Part Two (This library, AHRS_Joystick only work with the Pololu minIMU-9 v3 and v5 only). Don't forget to un-comment and comment the correct IMU version.

The Arduino (Pro Micro, Mega 32U4 chipset) can be turn into a Windows joystick device, automatically detected once plugin. You need Matthew Heironimus joystick library installed.
Which can be install from the library manager(recommended method) or manually.
https://github.com/MHeironimus/ArduinoJoystickLibrary

1. Make a backup copy of your existing AHRS and calibration values. (It not a bad idea to obtain new calibration once very full moon)
2. Download the Joystick Part_2 in the Download section, Compile and Upload the Sketch.
3. If all go well, You will see New hardware has been detected and USB driver will be installing.
4. Calibrate your new devices axis within Windows.
5. Remember to wait for 7-10 seconds for the device initiated and calculate the offset/tilt compensation values.
6. Change the input device to Joystick input and start in Opentrack.
7. Check your Axis Assignment if the the little Octupus is not moving. See picture
8. You no longer need to Start the Arduino and the Serial Monitor, just plug and play.Joystick as an input device.JPGNew Axis assignment Maybe Required.JPG


Part three (MPU9250 Joystick library) to be continue

Credit and Thanks to:

Jim_Remington
(https://forum.pololu.com/t/state-of-...rs-for-25/8091)
(https://forum.arduino.cc/index.php?topic=504435.0)

Kris/Paul Greg (Never got it to work)
(https://planetkris.com/2014/12/easie...-head-tracker/)

Mikhail Z (Mikhail Zakaluzhsky)
(http://zakamik-ru.blogspot.com/2014/...g-post_30.html)

Furax49 (http://hatire.sourceforge.net/)
v4friend (FaceTracknoIR)
(https://sourceforge.net/u/v4friend/profile/)
(https://sourceforge.net/projects/ftrgy86/files/)

Moeburn and MHeironimus
(https://www.youtube.com/watch?v=DCTt...gv3l0W8KSjW4vA)
https://github.com/MHeironimus (HID/Joystick library)
https://github.com/MHeironimus/ArduinoJoystickLibrary

D.Falck and RobertTech (for the Awesome library)
http://dfalck.xyz/arduino-quadcopter...usion-library/
(https://richardstechnotes.wordpress.com/)

And many other folks
(https://sourceforge.net/p/facetrackn...read/eced1cb2/)
(https://github.com/opentrack/opentrack/issues/139)
(https://github.com/opentrack/opentrack/issues/139)

[ATAG_Highseas]

I love these kind of threads.

Those arduino boards are great!